This invention relates to an ultrasonic diagnostic system for obtaining blood flow velocity information using an ultrasonic Doppler technique.
Recently, it has been known that it is effective to observe the blood flow velocity through the heart simultaneously with obtaining a tomogram, particularly a tomogram of the heart based on ultrasonic pulse echo from the object. As a method of ultrasonically detecting the blood flow state, there is a pulse modulated Doppler technique which has excellent distance resolution.
A system for obtaining blood flow velocity information is disclosed in U.S. Pat. No. 4,217,909 by Emmanuel Papadofrangakis et al. With this system, real time observation of blood flow velocity at a given point in the body can be obtained. However, it is impossible to observe one-dimensional or two-dimensional blood flow velocity distribution.
Marco Brandestini, "Topoflow-A Digital Full Range Doppler Velocity Meter", IEEE Transactions On Sonics And Ultrasonics, Vol. SU-25, No. 5, September 1978, PP. 287-293, discloses a system for obtaining the blood flow velocity distribution in the blood vessel. In this equipment, a Doppler shift signal is separated from a Doppler signal using a digital filter, and the two-dimensional blood flow velocity distribution in a predetermined period of time is obtained by means of frequency analysis of the signal. This equipment requires a circuit for the frequency analysis, therefore, the circuit construction is complicated. Also, the blood flow velocity information cannot be displayed in real time because the blood flow velocity distribution at a fixed time is detected.